The purpose of this study is to investigate the slippage mechanism of the pre-treatment of Smith's fracture and to evaluate the causal relation between the slippage and fracture reposition under palmar/dorsal flexion. A special designed experimental setup was used to simulate palmar/dorsal flexion motion of cadaver wrist and to measure the contact pressure distribution on the radiocarpal joint with pressure sensors. Comparison of the pressure distribution was made between the intact and Smith's fracture simulated. It was shown from the results that the pressure area for the case of Smith's fracture simulated shifted palmar side, and high pressure area partially appeared under palmar flexion motion.